Cell Phone Use Linked To Brain Tumor

(ENS) -- A study from the Institute of Environmental Medicine at Karolinska Institute, Sweden has found that 10 years or more of mobile phone use increases the risk of a benign tumor of a nerve in the brain. The tumors were found on the side of the head where the phone was usually held. No indication of an increased risk for less than 10 years of mobile phone use were found.

The increased risk of a tumor of the auditory nerve, called an acoustic neuroma, was found to be about four times higher on the side of the head where the phone was held, and virtually normal on the other side, the researchers said on October 13.

The study of 148 acoustic neuroma patients and 600 healthy people, included for comparison, was conducted by a team led by Dr. Maria Feychting and Professor Anders Ahlbom, professor of epidemiology and deputy director of the Institute of Environmental Medicine at Karolinska.

In his paper, Ahlbom reports that there may still be a risk from the short term use of cell phones. "We cannot exclude the possibility that short term exposure has an effect that can be detected only after a long latency period," he writes.

Approximately one in 100,000 people develop acoustic neuromas. This type of tumor grows slowly and accounts for less than 10 percent of all brain tumors. Because these tumors do not involve invasive growth, they are not classified as cancer.

Hand-held wireless phones with built-in antennas, known as mobile phones, or cell phones, emit low levels of radiofrequency energy in the microwave range while being used. The auditory nerve is exposed to radiation during the normal use of a cell phone.

"These are strong data,"Ahlbom told "Microwave News," a monthly publication based in New York which covers the health effects of electromagnetic radiation. "Just how strong will be determined in the upcoming post-publication assessment."

It is possible that other types of brain tumors might result from mobile phone use, and more study is needed, Ahlbom said. "If acoustic neuromas are possible, then the argument that effects are biologically implausible does not apply, and we don?t know what is possible."

The Karolinska Institute results are different from previous mobile phone studies, particularly a five year study undertaken in the 1990s by the National Cancer Institute (NCI) in the United States.

From 1994 to 1998, Peter Inskip and Martha Linet, M.D. of NCIs Division of Cancer Epidemiology and Genetics conducted a study of brain tumor risk among 782 people who had used hand-held cellular phones compared to 799 people who had not used them. The researchers looked at three tumor types -- acoustic neuroma, glioma, and meningioma.

"There was no evidence of increasing risk with increasing years of use or average minutes of use per day, nor did brain tumors among cellular phone users tend to occur more often than expected on the side of the head on which the person reported using their phone," the NCI scientists found. "Specifically, there was no indication of increased risk associated with use of a cell phone for one hour or more per day, for five or more years, or for cumulative use of more than 100 hours."

But Inskip and Linet did not rule out the possibility that tumors due to cell phone use could be found for use over periods of time longer than five years.

"If there is an increased risk of brain tumors due to use of cellular phones that only appears after five or more years, or only among very heavy users, it is probable that this study would have failed to detect it," they wrote.

The new Karolinska Institute study, which appears in the November issue of "Epidemiology," is part of the 13 nation Interphone study coordinated by the International Agency for Research on Cancer (IARC) in Lyon, France, the World Health Organization's cancer research institute.

The multicenter, international case-control IARC study, involving about 3,000 cases and 3,000 controls, is the largest study of the relationship between mobile phone use and tumors underway anywhere in the world.

All the Interphone study teams, including Feychting and Ahlbom' s, will report on the risk of the most common types of brain tumors such as astrocytomas and meningiomas.